ProQ-dependent activation of Salmonella virulence genes mediated by post-transcriptional control of PhoP synthesis

ABSTRACTGastrointestinal disease caused by Salmonella enterica is associated with the pathogen’s ability to replicate within epithelial cells and macrophages. Upon host cell entry, the bacteria express a type-three secretion system encoded within Salmonella pathogenicity island 2, through which host...

Full description

Bibliographic Details
Main Authors: Sofia Bergman, Liis Andresen, Jonas Kjellin, Yolanda Martinez Burgo, Petra Geiser, Sophie Baars, Fredrik Söderbom, Mikael E. Sellin, Erik Holmqvist
Format: Article
Language:English
Published: American Society for Microbiology 2024-03-01
Series:mSphere
Subjects:
Online Access:https://journals.asm.org/doi/10.1128/msphere.00018-24
_version_ 1797221955550576640
author Sofia Bergman
Liis Andresen
Jonas Kjellin
Yolanda Martinez Burgo
Petra Geiser
Sophie Baars
Fredrik Söderbom
Mikael E. Sellin
Erik Holmqvist
author_facet Sofia Bergman
Liis Andresen
Jonas Kjellin
Yolanda Martinez Burgo
Petra Geiser
Sophie Baars
Fredrik Söderbom
Mikael E. Sellin
Erik Holmqvist
author_sort Sofia Bergman
collection DOAJ
description ABSTRACTGastrointestinal disease caused by Salmonella enterica is associated with the pathogen’s ability to replicate within epithelial cells and macrophages. Upon host cell entry, the bacteria express a type-three secretion system encoded within Salmonella pathogenicity island 2, through which host-manipulating effector proteins are secreted to establish a stable intracellular niche. Transcription of this intracellular virulence program is activated by the PhoPQ two-component system that senses the low pH and the reduced magnesium concentration of host cell vacuoles. In addition to transcriptional control, Salmonella commonly employ RNA-binding proteins (RBPs) and small regulatory RNAs (sRNAs) to regulate gene expression at the post-transcriptional level. ProQ is a globally acting RBP in Salmonella that promotes expression of the intracellular virulence program, but its RNA repertoire has previously been characterized only under standard laboratory growth conditions. Here, we provide a high-resolution ProQ interactome during conditions mimicking the environment of the Salmonella-containing vacuole (SCV), revealing hundreds of previously unknown ProQ binding sites in sRNAs and mRNA 3′UTRs. ProQ positively affected both the levels and the stability of many sRNA ligands, some of which were previously shown to associate with the well-studied and infection-relevant RBP Hfq. We further show that ProQ activates the expression of PhoP at the post-transcriptional level, which, in turn, leads to upregulation of the intracellular virulence program.IMPORTANCESalmonella enterica is a major pathogen responsible for foodborne gastroenteritis, and a leading model organism for genetic and molecular studies of bacterial virulence mechanisms. One key trait of this pathogen is the ability to survive within infected host cells. During infection, the bacteria employ a type three secretion system that deliver effector proteins to target and manipulate host cell processes. The transcriptional regulation of this virulence program is well understood. By contrast, the factors and mechanisms operating at the post-transcriptional level to control virulence gene expression are less clear. In this study, we have charted the global RNA ligand repertoire of the RNA-binding protein ProQ during in vitro conditions mimicking the host cell environment. This identified hundreds of binding sites and revealed ProQ-dependent stabilization of intracellular-specific small RNAs. Importantly, we show that ProQ post-transcriptionally activates the expression of PhoP, a master transcriptional activator of intracellular virulence in Salmonella.
first_indexed 2024-04-24T13:13:39Z
format Article
id doaj.art-2452475d32424a88af6d63d1840b3985
institution Directory Open Access Journal
issn 2379-5042
language English
last_indexed 2024-04-24T13:13:39Z
publishDate 2024-03-01
publisher American Society for Microbiology
record_format Article
series mSphere
spelling doaj.art-2452475d32424a88af6d63d1840b39852024-04-05T01:32:10ZengAmerican Society for MicrobiologymSphere2379-50422024-03-019310.1128/msphere.00018-24ProQ-dependent activation of Salmonella virulence genes mediated by post-transcriptional control of PhoP synthesisSofia Bergman0Liis Andresen1Jonas Kjellin2Yolanda Martinez Burgo3Petra Geiser4Sophie Baars5Fredrik Söderbom6Mikael E. Sellin7Erik Holmqvist8Department of Cell and Molecular Biology, Biomedical Center, Uppsala University, Uppsala, SwedenDepartment of Cell and Molecular Biology, Biomedical Center, Uppsala University, Uppsala, SwedenDepartment of Cell and Molecular Biology, Biomedical Center, Uppsala University, Uppsala, SwedenDepartment of Cell and Molecular Biology, Biomedical Center, Uppsala University, Uppsala, SwedenDepartment of Medical Biochemistry and Microbiology, Science for Life Laboratory, Uppsala University, Uppsala, SwedenDepartment of Cell and Molecular Biology, Biomedical Center, Uppsala University, Uppsala, SwedenDepartment of Cell and Molecular Biology, Biomedical Center, Uppsala University, Uppsala, SwedenDepartment of Medical Biochemistry and Microbiology, Science for Life Laboratory, Uppsala University, Uppsala, SwedenDepartment of Cell and Molecular Biology, Biomedical Center, Uppsala University, Uppsala, SwedenABSTRACTGastrointestinal disease caused by Salmonella enterica is associated with the pathogen’s ability to replicate within epithelial cells and macrophages. Upon host cell entry, the bacteria express a type-three secretion system encoded within Salmonella pathogenicity island 2, through which host-manipulating effector proteins are secreted to establish a stable intracellular niche. Transcription of this intracellular virulence program is activated by the PhoPQ two-component system that senses the low pH and the reduced magnesium concentration of host cell vacuoles. In addition to transcriptional control, Salmonella commonly employ RNA-binding proteins (RBPs) and small regulatory RNAs (sRNAs) to regulate gene expression at the post-transcriptional level. ProQ is a globally acting RBP in Salmonella that promotes expression of the intracellular virulence program, but its RNA repertoire has previously been characterized only under standard laboratory growth conditions. Here, we provide a high-resolution ProQ interactome during conditions mimicking the environment of the Salmonella-containing vacuole (SCV), revealing hundreds of previously unknown ProQ binding sites in sRNAs and mRNA 3′UTRs. ProQ positively affected both the levels and the stability of many sRNA ligands, some of which were previously shown to associate with the well-studied and infection-relevant RBP Hfq. We further show that ProQ activates the expression of PhoP at the post-transcriptional level, which, in turn, leads to upregulation of the intracellular virulence program.IMPORTANCESalmonella enterica is a major pathogen responsible for foodborne gastroenteritis, and a leading model organism for genetic and molecular studies of bacterial virulence mechanisms. One key trait of this pathogen is the ability to survive within infected host cells. During infection, the bacteria employ a type three secretion system that deliver effector proteins to target and manipulate host cell processes. The transcriptional regulation of this virulence program is well understood. By contrast, the factors and mechanisms operating at the post-transcriptional level to control virulence gene expression are less clear. In this study, we have charted the global RNA ligand repertoire of the RNA-binding protein ProQ during in vitro conditions mimicking the host cell environment. This identified hundreds of binding sites and revealed ProQ-dependent stabilization of intracellular-specific small RNAs. Importantly, we show that ProQ post-transcriptionally activates the expression of PhoP, a master transcriptional activator of intracellular virulence in Salmonella.https://journals.asm.org/doi/10.1128/msphere.00018-24ProQCLIP-seqRNA-binding proteinsmall RNASalmonellavirulence
spellingShingle Sofia Bergman
Liis Andresen
Jonas Kjellin
Yolanda Martinez Burgo
Petra Geiser
Sophie Baars
Fredrik Söderbom
Mikael E. Sellin
Erik Holmqvist
ProQ-dependent activation of Salmonella virulence genes mediated by post-transcriptional control of PhoP synthesis
mSphere
ProQ
CLIP-seq
RNA-binding protein
small RNA
Salmonella
virulence
title ProQ-dependent activation of Salmonella virulence genes mediated by post-transcriptional control of PhoP synthesis
title_full ProQ-dependent activation of Salmonella virulence genes mediated by post-transcriptional control of PhoP synthesis
title_fullStr ProQ-dependent activation of Salmonella virulence genes mediated by post-transcriptional control of PhoP synthesis
title_full_unstemmed ProQ-dependent activation of Salmonella virulence genes mediated by post-transcriptional control of PhoP synthesis
title_short ProQ-dependent activation of Salmonella virulence genes mediated by post-transcriptional control of PhoP synthesis
title_sort proq dependent activation of salmonella virulence genes mediated by post transcriptional control of phop synthesis
topic ProQ
CLIP-seq
RNA-binding protein
small RNA
Salmonella
virulence
url https://journals.asm.org/doi/10.1128/msphere.00018-24
work_keys_str_mv AT sofiabergman proqdependentactivationofsalmonellavirulencegenesmediatedbyposttranscriptionalcontrolofphopsynthesis
AT liisandresen proqdependentactivationofsalmonellavirulencegenesmediatedbyposttranscriptionalcontrolofphopsynthesis
AT jonaskjellin proqdependentactivationofsalmonellavirulencegenesmediatedbyposttranscriptionalcontrolofphopsynthesis
AT yolandamartinezburgo proqdependentactivationofsalmonellavirulencegenesmediatedbyposttranscriptionalcontrolofphopsynthesis
AT petrageiser proqdependentactivationofsalmonellavirulencegenesmediatedbyposttranscriptionalcontrolofphopsynthesis
AT sophiebaars proqdependentactivationofsalmonellavirulencegenesmediatedbyposttranscriptionalcontrolofphopsynthesis
AT fredriksoderbom proqdependentactivationofsalmonellavirulencegenesmediatedbyposttranscriptionalcontrolofphopsynthesis
AT mikaelesellin proqdependentactivationofsalmonellavirulencegenesmediatedbyposttranscriptionalcontrolofphopsynthesis
AT erikholmqvist proqdependentactivationofsalmonellavirulencegenesmediatedbyposttranscriptionalcontrolofphopsynthesis